Further studies will be made concerning the chemical and physical characterization of 3 unusual histone subfractions which we have found in seminiferous epithelial cells of rat testis. Research will be continued on the effects of follicle stimulating hormone, interstitial cell stimulating hormone, and testosterone on the rate of synthesis of these histone subfractions in comparison with the usual histone fractions. A study will be made of the effects of various analogues of androgens and estrogens upon the synthesis of the unusual histone fractions and the protamines in rat testis. BIBLIOGRAPHIC REFERENCE: Changes in Basic Chromosomal Proteins During Spermatogenesis In the Mature Rat. K.K. Kumaroo, G. Jahnke, and J.L. Irvin, Arch, Biochem. Biophys., 168, 413-424 (1975).